In article <9409012138.AA65559 at acs4.acs.ucalgary.ca> msseyed at ACS.UCALGARY.CA ("Soheil Seyed Mahmoud") writes:
>Hi there. I have expressed a protein (ca 22kd) as a fusion with
>GST in E.coli. I can purify ther fusion protein on agarose bound
>glutathione beads. However, as I attempt to add the thrombin
>bufer (20mMtris (pH8.3), 5mM CaCl2, with or without 150mMNacl),
>the fusion protein precipitates out. Any suggestions how I can
>get over this problem? Thanmks a bunch.
>Soheil
You have a number of things to try here - the buffer specificty for
thrombin is fairly wide - Ive cut fusions in 50mM (NH4)2SO4, and in 50mM
Tris pH 7.6, and others Ive forgotten about. So I suggest as a first
attempt you leave out the calcium (it is *not* necessary) which I suspect
is your problem, and/or change the pH to something a little lower.
Good luck
RSol